Oral rehydration therapy (ORT) of diarrhea, while effective in correcting dehydration, is poorly accepted in many communities. One significant reason for this is the inability of conventional ORT to shorten diarrhea or reduce fecal fluid losses. The recent demonstration that short chain fatty acid (SCFA) stimulation of colonic Na-CI absorption is not inhibited by cyclic AMP suggested the possibility that colonic SCFA could provide an adjunct to standard ORT. We have recently found that resistant starch (i.e. starch that is relatively resistant to amylase), which is metabolized to SCFA in the colon, significantly reduces duration of diarrhea in adults with cholera. Since children often have diarrhea due to causes other than cholera, the proposed study will evaluate whether ORT with resistant starch will reduce fecal fluid losses and the duration of diarrhea in children with acute diarrhea. Two hundred and fifty-eight children with diarrhea and mild to moderate dehydration will be randomized to receive either standard treatment with glucose-ORS or treatment with glucose-ORS containing resistant maize starch 50 g/l. Both groups will be treated according to a standardized protocol recommended by the W.H.O., including refeeding after 4 hours of initial rehydration. The end-points will include measurement of fecal volumes and the time from admission to the last unformed stool, assessed by an observer who is blinded to the treatment received. Treatment failures will be categorized and recorded. If resistant starch is found to reduce fecal volumes and/or duration of diarrhea, this innovative therapy must then be tested in the community for acceptance.